BMW M four-cylinder engine unlikely, unless electrified

BMW’s M Division says it will not produce a small-capacity high-performance turbocharged four-cylinder engine until it can find the right way to counter the deficits of such a power unit with electrification.

Speaking to Australian media in Munich today, the boss of BMW’s M Division, Frank Van Meel, said the performance sub-brand is keen to maintain its six-cylinder power units despite rival Mercedes-AMG having made use of smaller capacity four-cylinder units.

“We are really happy with our six-cylinder [engines] because for BMW and BMW M that is our heritage engine. We started with six-cylinder in the M1 so it has a long history. BMW is a six-cylinder inline company and, for us, it’s an iconic engine,” Van Meel said.

“If you look at it with a four-cylinder, I don’t see characteristics that I would like on an M car, on a small displacement turbocharged four-cylinder engine. I wouldn’t do a four-cylinder standalone turbocharged with high performance, because you always have the characteristic that if you want high performance you lose the low-end torque and you lose the overall driveability you want to have from the car.”

Electrification, however, may prove to be the answer as it solves the initial lag and lack of torque that is generally on offer from a high-output but small-capacity turbocharged engine.

Even so, creating a hybrid powertrain has its own set of disadvantages.

“Electrification would help because low-end torque is done with electric motors. On the other hand, you are putting a lot of weight into the car, so that answer is not so easy. To say ‘just do it’, you lose the motorsport topic of power-to-weight ratio which is very important with overall weight.

“So, at the time-being, it’s a dilemma – but we are working on that with our project ‘i’ colleagues to have a look at the next generation of battery cells, regarding weight, power, density and range to find the right tipping point to say ‘now it makes sense to go in that right direction’… but today is not the right time.”

BMW has already confirmed it is looking to add electric motors to its M vehicles, however, Van Meel admits it would take some more evolution of the technology before it makes sense in future M models.

“With the current generation we see ‘E’ motors that are still not strong enough for M applications, and if you look at plug-in hybrids, it will add 2-300kg – which, for a car like an M3/M4 with 1500kg – would put that completely out of balance and we couldn’t rebalance that towards a typical M philosophy.

“So, with nowadays technology, we don’t see that [working], but I can’t tell you what the next steps with the BMW group will be.”

Tell us what you think

BMW currently offers six and eight cylinder turbocharged engines in its lineup of pure M and M-performance variants. Would a four-cylinder engine work in an M badged vehicle?